Reenforced hydrated cellulose container



Patented June 23, 1936 UNITED STATES PATENT OFFICE REENFORCED HYDRATEDCELLULOSE CONTAINER ginia No Drawing. Application February, 4, 1931,Serial No. 513,352

17 Claims.

The present invention is concerned primarily with the preparation andutilization of a unitary, or unitary appearing, partially transparentbody of an unmodified and modified cellulosic material,

or the combination of a structural and structureless cellulose body as acontainer for products intended for human consumption and is related tomy co-pending applications, Method of treating fibrous material, Ser.No. 442,443, filed April '7, 1930, which is now Patent Number 1,829,702,dated October 27, 1931; Reinforced hydrated cellulose fromnitrocellulose, Ser. No. 511,114, filed January 24, 1931; Reenforcedhydrated cellulose from acetylcellulose, Ser. No. 511,113, filed January24, 1931; Reenforced hydrated cellulose from viscose, Ser. No. 511,452,filed January 26, 1931.

This invention relates to improvements in methods of treating vegetablefibrous material and the products obtained therefrom, especially inconnection with the treatment of those types of fibrous materialprepared from, or having the characteristics of those fibers known asmitzumata, kodzu, gampi and by other names, and other similar plants andtypes of plants and of fibers obtained therefrom, with soluble organicsulfur derivatives of cellulose, as viscose (alkali salt of xanthatedcellulose) which soluble derivative is subsequently regenerated, withthe formation of a regenerated cellulose product, which forms a unitary,translucent body or compound with the above stated fibers, irrespectiveof whether said fibers are in the individual state,

loosely commingled, or in the matted aggregate.

condition, and the employment of the finished product as a wrapper casecontainer or casing for the storage and preservation of edible products,either animal or vegetable.

It is well known that so-called regenerated celluloses, in general,readily absorb moisture. "i In this condition the tensile strength andother desirable physical properties are materially impaired, and thisdisadvantage of such regenerated celluloses has heretofore materiallynaryrowed the scope of their technical usefulness, for

example, in such arts as the sausage casing inadustry, as a substitutefor the natural gut of ianimals now used for this purpose.

One of the objects of this invention is to so 50 reenforce, fortify andstrengthen this regenerated cellulose material ormembrane that itstensile strength, resistance to rupture, and other valuablecharacteristics are considerably augmented, both in the dry and moistcondition, without at the 55 same time materially detracting from thevaluable properties of the regenerated cellulose, and in so doing notonly to increase its usefulness in arts in which it may now be employed,but to extend its usefulness to arts in which, up to the present, it hasnot been used to any considerable extent.

As typical of the organic esters of cellulose containing sulfur, thisinvention is limited to the use of the esters of cellulose with thexanthic acid radical, the so-called cellulose xanthates orsulfocarbonates, in which the cellulose has been esterified under suchconditions as to be soluble in, or miscible with, weak alkali metalhydroxides in aqueous solution, and not incompatible with softeners, asnow used in the cellulose xanthate or viscose art.

Another object of my invention is to combine in a pellucid, orsemi-transparent, unitary-appearing layer of indeterminate dimensions asto thickness, length and width, fibers as above stated, in theirindividual fibrous condition, or when agglomerated, agglutinated, oraggregated, or in the form of sheets containing a multiplicity of thefibers and made by ways now known, the fibers being either in anuntreated, undyed, partially dyed or dyed condition, with a xanthatedcellulose in solution or viscose which is afterwards regenerated,suitably by acid treatment, resulting in the formation as the finishedpreparation of a cellulose material not hydrated and cellulose in a moreor less hydrated condition, the two classes of materials being united toa uniformly appearing unitary body or sheet. If the cellulosic fibersare dyed, it is to be understood that said fibers may all be dyed onecolor or shade, or of two or more colors or shades to produce new andnovel effects. The coloring matter used, of course, must not bedeleteriously affected by the chemicals employed in the subsequentoperations.

Another object of this invention is the preparation of cylindrical,rectangular or other shaped lengths, of uniform or varying diameter orlength, of fibers of the nature specified, in the individual, matted oragglomerated condition, undyed, dyed or otherwise colored ormodified inproperties and in appearance, treated, coated or impregnated withviscose, which is regenerated to form a combined layer or body ofunmodified or fibrous cellulose and of cellulose which has been modifiedin its chemical and physical characteristics.

Hydrated cellulose, being inert, and substantially permanently stable,is especially advantageous in comparison with protective coatings of thecellulose esters which heretofore have been 55 proposed for thispurpose, certain of which may undergo slow decomposition and formundesirable decomposition products.

The finished material has to a high degree the desirable properties ofnatural gut, in strength, elasticity, flexibility, pliability andporosity, and like natural animal membrances, possesses the uniqueproperty of high expansion in the moistened condition and contractionwhen dried. It has also been found to satisfactorily meet the exactingrequirements of casings when smoking, curing, and boiling processes areinvolved.

The casings made by my process of the present invention have increasedtensile strength even in the wetted condition. In case of a break ortear, because of this fibrous base or-intermediary reenforcing layer,further progress of any break or tear is retarded, and its arearestricted.

The product of this invention therefore, is especially practicable foruse in a tubular or other shaped container for foods intended for humanconsumption, altho it is to be understand that the material comprising anormal and a modified cellulose material may be used for receiving andpreserving substances of a non-edible nature, or, in fact, wherever andwhenever a container or material with properties of natural gut andother animal membranes is required, irrespective of the nature of thematerial contained therein.

The well known abnormal strength of the class of fibers comprehended inthis invention, their suppleness, ready permeability by means ofcellulose xanthate in the dissolved condition or viscose, and theirpliability and other valuable physical characteristics in theimpregnated state, when combined with a cellulosic material neutral inreaction, having inherent strength, expansibility and contractility of ahigh degree, produces a combination of desirable physicalcharacteristics and chemical department highly advantageous in thosetechnical arts such as the sausage casing industry, wherein relativelyhigh tensile strength, a well defined porosity, high expansibility andcontractility, indestructibility, insolubility in water and all knownvolatile solvents or solvent combinations without change, are valuabledesiderata.

Another object of this invention is the production of capsules orcasings, tubular or otherwise, neutral and diaphanous, especiallyapplicable as containers for edible products or for products notintended for human consumption, simulating animal membrane inappearance, properties and usefulness, and having the desired tensilestrength, flexibility, pliability and porosity, and the ability toundergo relatively high expansibility and contractility under normalmethods of commercial application without rupturing or substantial lossin strength.

In contradistinction to natural or animal membranes which have beenproposed and used for the temporary preservation of food products, theclasses of fibers enumerated herein, when homogeneously impregnated andcovered with a body of stable regenerated cellulosic material as hereindescribed, are antiseptic and aseptic, not prone to deterioration fromnormal atmospheric infiuences, and are especially applicable for thispurpose by virtue of its physical characteristics as enumerated herein.

If an imprint is to be placed on the finished article, said imprint maybe made upon the cellulose fibrous matrix or sub-structure before theapplication of the viscose, or upon the regenerated cellulose layer. Atany stage of the process,

the sheets, film or layer, may be corrugated, embossed or otherwisegiven a surface pattern.

By virtue of the opalescence and translucency of the cellulosic fibers,the finished integument, layer, sheet or film is never whollytransparent, although the degree of translucency and nearness totransparency may be varied within wide limits as will be readilyunderstood by those conversant with the art to which this inventionappertains. If it is desired to more nearly approach transparency, thefibrous material may be mercerized or otherwise treated chemically orits opalescency may be diminished by treatment with oils or oleaginousmixtures, before the viscose is applied thereto and thereon; or theopalescency may be diminished in other ways.

The major portion of cellulose xanthate prepared at the present time isfor viscose rayon production. In the viscose solution, during the ageingor ripening process, the usual free alkali content is 6%7 NaOI-I. It hasbeen found that this amount of alkali is prone to soften the fiberscomprehended in this invention to the extent that it is diificult tocoat and impregnate them in the matted or fibrous-condition. I thereforeprefer to use a viscose solution for this purpose which contains thereina minimum of free alkali, about 3% having been found satisfactory. It isalso essential for best results that after the close of the xanthationperiod in viscose formation, great pains be taken to remove the free oruncombined carbon bisulfide.

The material produced by the present invention may be prepared by firstimpregnating or depositing on and in a vegetable fibrous structure asuitable organic sulfur-containing ester of cellulose which is solublein water and in diluted solutions of alkali metal salts, and thenregenerating the cellulose or group contained therein, or else byadmixing the suitable fibers in individual pulp form, with thesulfur-containing cellulose ester in solution and then regenerating thecellulose by removing the acidic radical formerly attached to thecellulosic portion.

While specifically the vegetable fibers used in the present inventionmay be prepared from the plants mitzumata, kodzu (kozo) and gampi(ganpi) being plants of the Edgeworthia, Broussonetia and Wilkstroemiafamilies respectively, and it is to be understood that any other fibershaving similar characteristics may be employed for this purpose withinthe limitations of this invention.

Fibers from these plants, comprise relatively long thin cells of greatsuppleness and strength, and are little affected, comparativelyspeaking, by the chemicals and solutions used in carrying this inventioninto effect.

In carrying my invention into effect, the following two general examplesindicate two of the preferred methods of practicing the same, but it isto be understood that these two examples are merely given forillustrative purposes and may be varied within comparatively widelimits.

Example I .-A mat or sheet of cellulosic fibers of the nature abovereferred to such as Yoshino or Japanese cobweb paper in sheet or rollform, and. of any desired width and thickness is immersed in--a so-called viscose solution containing the equivalent of about 6%cellulose, and about 3% sodium hydroxide,the solution being ofrelatively low viscosity and suitably at the temperature of the room.Where the viscose solution is kept at 20 C. and lower, there is lesssoftening of the fibers than when a higher temperature during immersionis resorted to. Better results are also obtained by subjecting theviscose solution to a vacuum treatment for an hour or longer in order toremove the major portion of the air bubbles and dissolved air in thesolution.

If it is desired to strengthen the fibrous base before applying theretothe viscose solution, this may be accomplished in several ways, thefibrous base may be superficially acetylated or nitrated or gherwiseesterified'afid tlif'str radical removed by hydroIysis;"The fibrousportion may also be strengthened by applying thereto a dilute celluloseester solution in a non-aqueous, volatile solvent or solventcombination, leaving a deposit of the cellulose ester, from which theacid radical may be removed by hydrolysis before the application of theviscose solution. In practice I have obtained excellent results byspraying the fibrous cellulose with a solution of cellulose acetate asby an air brush or airspray, and have found that with the comparativelysmall amount of cellulose acetate required, it is unnecessary to removethe acetic acid by a separate de-esterification treatment.

However, I may submit the sheet thus superficially coated with thecellulose ester to a saponifying treatment, to remove the acetic acidtherefrom before submitting the sheet to impregnation with viscosesolution.

After applying the viscose solution to the fibrous sheet, the latter isimmediately immersed in a warm, acid setting bath, similar incomposition to that used in the viscose rayon industry, I having found abath consisting primarily of 10%-12% sulfuric acid and at a temperatureof about 42 C. satisfactory for the purpose. After immersion in thehydrolyzing bath it is expedient to allow the sheet to stand for sometime to ensure uniform and complete penetration of acid andneutralization of alkali and regeneration of the cellulose. Thetranslucent, milky appearing sheet is next washed until neutral,immersed in an alkali metal sulfide bath at about 45 C. and containing10-12 grams sodium sulfide per liter to remove the sulfur containedtherein, and washed free from sulfur. If it is desired to impart addedsuppleness and flexibility, the sheet may be immersed in an appropriatesolution such as one of glycerol, glycol, glucose or other similarmaterial, and the excess moistureremoved in any convenient manner.

If it is desired that the final sheet shall be more nearly transparent,the sheet of matted fibers may be subjected to a preliminary chemicaltreatment as by a mercerizing bath under carefully regulated conditionsin order to guard against softening and disintegration of the sheet, thereactants removed, and the sheet deprived of extraneous moisture. Or thesheet may be rendered translucent by other treatment prior toimpregnation with viscose solution.

If a colored efiect is sought, the fibrous cellulose may be coloredbefore impregnation, or coloring matter may be dissolved in the aqueousalkali used to bring the xanthated cellulose into solution, or thehydrated cellulose may be dyed. The coloring material may comprisedyestuffs, lakesor pigments or a mixture of soluble and insoluble colormay be employed.

Example II.-A suitable amount of loose, not matted fiber, of the classcomprehended in this invention, depending upon the ratio of fibers toregenerated cellulose desired in the finished product, is intermingledor stirred with the desired amount of viscose solution of thecharacteristics desired. When the fibers are uniformly disseminated inthe syrupy mixture, the liquid is poured on a smooth surface and thenimmersed in a setting bath as heretofore indicated, or the mixture iscast upon a movable hard smooth surface and then precipitated. Theamount of total solids deposited upon a given area will depend primarilyupon the percentage of non-evapo-rable solids in the viscose solutionand the viscosity of the same.

In certain cases, and where especial effects are to be obtained, thematted fibrous base mentioned in Example I may be used, and the solutionof viscose with individual fibers admixed therewith as outlined inExample II, may be substituted for the plain viscose solution indicatedin Example I.

If it is desired to form the finished article in a tubular or otherclosed form, a tube may be formed in any suitable way, as for instance,by slipping the fibrous portion over a hollow mandrel and then immersingmandrel and contents in the viscose solution as above indicated, or ifthe fibers are in the loose condition in the viscose solution, they maybe deposited on a mandrel or other suitable form, and the viscosecoagulated by precipitation as has been outlined.

Having now described my invention which is the production of anon-transparent film comprising a structural and structurelesscellulosic body, or the combining of a normal cellulose with modifiedcellulose devoid of organic acid radical, and in what manner the samemay be performed, what I claim as new, and desire to secure by LettersPatent is:-

1. The method of producing a container for edible products comprising,lightly impregnating a long-fibered material in. tubular form with adilute acetylated cellulose dissolved in a nonaqueous solution,evaporating the volatile solvent, then homogeneously impregnating andcovering the stiffened tube with a solution of viscose con taining about3% free alkali-metal hydroxide, immersing said tube in an acidprecipitating bath, washing free from reacting chemicals and allowing todry whereby a tube is formed in which the fibers serve as a reinforcingstructure.

2. The method of producing a container for edible products whichcomprises, lightly impregnating a long-fibered material in tubular formwith a dilute acetated cellulose dissolved in a non-aqueous solution,evaporating the volatile solvent, impregnating the tube with a solutionof viscose to homogeneously impregnate and cover the tube, immersing thetube in an acid precipitating bath, washing free from reactingchemicals, and allowing to dry whereby a tube is formed in which thefibers serve as a reinforcing structure.

3. The method of producing a container for edible products whichcomprises, treating a longfibered material in tubular form with asolution of xanthated cellulose having a minimum content of free alkalito homogeneously impregnate and cover the tube and regenerating thexanthated cellulose to form an impregnation of regenerated cellulose inand on the fibrous base whereby a tube is formed in which the fibersserve as a reinforcing structure.

4. The method of treating a fibrous base prepared from mitzumata, kodzu,gampi or other similar plants which comprises impregnating the base witha viscose solution to homogeneously impregnate and cover the same andthen substantially or completely regenerating the cellulose as aninsoluble film withthe fibrous base as a reenforcing layer.

5. The method of producing a casing for edible products which comprisestreating a tube of fibrous material prepared from mitzumata, kodzu,gampi or other similar plants with aviscose solution tohomogeneously'impregnate and cover the same and then regenerating thecellulose as an insoluble tubular film with the fibrous base as areenforcing layer.

6. The method of forming a casing for meat and other edible productswhich comprises applying a viscose solution to a tissue-like sheet ofmatted long-fibered cellulose to homogeneously impregnate and cover thesame and regenerating the cellulose to form a film having said fibroussheet as an intermediate reenforcing layer.

'7. The method of forming a casing for sausages and other edibleproducts which comprises treating a tube of matted long-fiberedcellulose with a viscose solution to cover and homogeneously impregnatethe same and subsequently regenerating the cellulose to form a tubularfilm having said fibrous sheet as a reenforcing layer.

8. The method of forming a casing for sausages and other edible productswhich comprises forming a tissue-like sheet of matted cellulose fibersprepared from mitzumata, kodzu, gampi or other similar plants, applyinga viscose solution thereto to homogeneously impregnate and cover thesame, and regenerating and drying the cellulose to form a film havingsaid fibrous sheet as a reenforcing layer. 1

9. The method of forming a container or casing for meat and other edibleproducts which comprises immersing long-fibered tissue paper in aviscose Emmi 6?; containing about 6% cellulose to homogeneouslyimpregnate and cover the same, then immersing the paper and appliedviscose coating in a suitable setting bath, and washing and drying theresulting product, thereby forming a film-like casing with said paper asa reenforcing layer.

10. The method of forming a container or casing for meat and otheredible products which comprises immersing long-fibered tissue paper in aviscose solution containing about 6% cellulose to homogeneouslyimpregnate and cover the same, then immersing the paper and appliedviscose coating in a suitable setting bath, washing the resultingproduct, applying a softening agent thereto and drying it, therebyforming a film-like casing having said paper as a reenforcing layer.

11. A method of producing a material having the properties of asynthetic gut which comprises mixing vegetable fibers as such withviscose to homogeneously impregnate and cover the fibers, forming themixture to produce a film, and subjectin'g the film to the action of asetting bath and subsequently washing and drying the resulting film,said fibers serving as an intermediate reenforcing structure.

12. The method of producing a casing for meat and other edible productshaving properties simulating those of a natural casing which comprisesmixing vegetable fibers as such with viscose solution to homogeneouslyimpregnate and cover the fibers, forming the mixture to produce atubular film,'subjecting the tubular film to the action of a suitablesetting and regenerating bath and drying the resulting product, therebyforming a tubular film of regenerated viscose united with the fibers inwhich the fibers serve as a reenforcing structure.

13. The method of preparing a thin sheet of material suitable for use ascasings which comprises] treating long-fibered cellulose material withviscose to homogeneously impregnate and cover the same and regeneratingcellulose from the viscose to provide a regenerated cellulose sheethaving an intermediary reenforcing structure of fibers.

14. The method of preparing a, thin sheet of material suitable for useas casings which comprises treating fibers obtained from mitzumata,kodzu, gampi or other similar plants with viscose to homogeneouslyimpregnate and cover the same and regenerating cellulose from theviscose to provide a regenerated cellulose sheet having anintermediary'reenforcing structure of fibers.

15. The 'method of preparing a thin sheet of material in tubular formsuitable for use as casings which comprises forming a tissue oflongfiber cellulose material into a tube and treating said tube ofceliulose material with viscose to homogeneously impregnate and coverthe same and regenerating cellulose from the viscose to provide a tubeof regenerated cellulose sheet material having an intermediaryreenforcing structure of fibers.

16. Asa casing, a tubular film composed of regenerated cellulosereenforced by tissue-like longfibered cellulose material prepared fromthe process which comprises, treating long-fibered cellulose-withviscose to homogeneously impregnate and cover the same and regeneratingcellulose from the viscose to provide the regenerated cellulose sheethaving the intermediary reenforcing structure of fibers.

17. As a new article of manufacture, a film composed of regeneratedcellulose reenforced by tissue-like long-fibered celluiose materialprepared from the process which comprises, treating longfiberedcellulose with viscose to homogeneously impregnate and cover the sameand regenerating cellulose from the viscose to provide the regeneratedcellulose sheet having the intermediary reenforcing structure of fibers.

LEO A. GOODMAN.

